The nuclei of Plasmodium yoelii nigeriensis contain an enzyme, ADP-ribosyltransferase, that will incorporate the ADP-ribose moiety of NAD+ into acid-insoluble product. The time, pH and temperature optima of this incorporation are 30 min, 8.5 and 25 degrees C respectively. Maximum stimulation of the enzyme activity is obtained with 1.0 mM-dithiothreitol or 2.0 mM-2-mercaptoethanol. Ca2+ and Mg2+ ions at optimum concentrations of 5 mM and 10 mM respectively stimulated the activity of the enzyme by 21% and 91%. The enzyme activity is, however, inhibited by 24% in the presence of 10 mM-MnSO4. The substrate, NAD+, exhibits an apparent Km of 500 microM, and the activity of the enzyme is inhibited by four chemical classes of inhibitors: nicotinamides, methylxanthines, thymidine and aromatic amides. The inhibitors are effective in the following increasing order: nicotinamide less than 3-aminobenzamide less than thymidine less than 5-methylnicotinamide less than theophylline less than m-methoxybenzamide less than theobromine. The enzyme activity is also inhibited by some DNA-binding anti-malarial drugs.
Research Article| March 01 1983
ADP-ribosyltransferase in Plasmodium (malaria parasites)
Biochem J (1983) 209 (3): 687–693.
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E E Okolie, N I Onyezili; ADP-ribosyltransferase in Plasmodium (malaria parasites). Biochem J 1 March 1983; 209 (3): 687–693. doi: https://doi.org/10.1042/bj2090687
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